There is conventionally known an image reading apparatus having a configuration including a first reading unit and a second reading unit. Further, in this image reading apparatus, a first block member and a second block member are provided one above the other across a conveying path. The first reading unit is retained in the first block member with a first reading surface thereof facing the conveying path. The second reading unit is retained in the second block member with a second reading surface thereof facing the conveying path.
When an upper surface of a sheet passes on the first reading surface while the sheet is conveyed along the conveying path, an image on the upper surface is read by the first reading unit. Further, when a lower surface of the sheet passes on the second reading surface while the sheet is conveyed along the conveying path, an image on the lower surface is read by the second reading unit.